Add a Feature

Add a new feature to an existing product, as seamlessly as possible.

Team Size

2–3 people


5–6 days


  • Index cards
  • Pens
  • Digital design tool
  • Interface animation prototyping tool
  • Presentation software


  • High-fidelity mockups
  • Click-through prototype of a “happy path”
  • Presentation

Target Device

Mobile App (Either iOS or Android)


You’ve been tasked with adding a new feature to an existing product. The feature may have already been decided on, but that doesn’t mean that conducting some initial research is irrelevant! Decisions like this are often made for all sorts of reasons (business goals, marketing needs, keeping up with the competition), and it’s our job to find ways to still make our work as user-centered as possible. Dig deeper to find out what user goals this feature may really be aimed at, so that you can make a stronger design.


As a new designer joining a team, you’ll often have to rapidly familiarize yourself with your product, your users, and quickly iterate on proposed solutions under tight timelines. Your other stakeholders will all have opinions, and you’ll have to get into the practice of supporting your claims and finding ways to incorporate new features into the existing platform.

Aspects to Consider



We should get a strong sense of:

Suggested Schedule

Day 1

  • Make a project plan
  • Define user research methods (surveys, interviews…) and execute
  • Benchmarking

Day 2

  • Continue research and benchmarking
  • Heuristics & CRAP
  • Define problem and user
  • Define new user flow with added feature

Day 3

  • Paper prototype
  • Test & iterate

Day 4

  • Mid-fidelity prototype
  • Test & iterate

Day 5

  • Test & iterate
  • High-fidelity mockups
  • Principle animations
  • Interactive prototype
  • Test & iterate

Day 6

  • Finalize your design
  • Prepare presentation and rehearse
  • Present your work

Design Thinking

Remember that design challenges are tackled by alternating divergent and convergent thinking modes. You are expected to conduct exploratory research and narrow down the scope of the problem within the realm of the proposed feature. Then generate multiple possible solutions. Evaluate. Test. Repeat. You’ll have the opportunity to show these iterations in your presentation.